It is well known that a wireless channel may cause an arbitrary time dispersion, attenuation, and phase shift in the received signal during wireless communications. The use of orthogonal frequency-division multiplexing and a cyclic prefix mitigates the effect of time dispersion. However, it may still be necessary to remove the amplitude and phase shift caused by the channel if one wants to apply linear modulation schemes, such as the ones used in WiMAX (Worldwide Interoperability for Microwave Access), to encode/decode the message.
In an OFDM system, channel estimation generates an estimate of the amplitude and phase shift caused by the wireless channel from the available pilot information. An accurate estimate may be employed to successfully remove the effect of the wireless channel and allow subsequent symbol demodulation.